1. Field of the Invention
The present invention relates to a brake assembly for use in a washing machine, and more particularly, to a brake assembly of a washing machine capable of amending an error of a braking operation caused by an assembly tolerance and/or an abrasion of a brake band.
2. Prior Art
FIG. 6 is a partial sectional view of a conventional washing machine, which shows a pulsator, a shaft assembly, and a driving motor, and FIG. 7 is a partial enlarged transverse sectional view of FIG. 6, which shows a brake assembly.
A washing machine has an outer tub 101 suspended in a casing, a spin basket 103 rotatably installed in the outer tub 101, and a pulsator 105 installed in the spin basket 103. A driving motor 107 is installed under the outer tub 101. Between the outer tub 101 and the driving motor 107, a shaft assembly 109 for transmitting the driving force of the driving motor 107 to the pulsator 105 and the spin basket 103, and a clutch assembly 111 for controlling the transmission of the driving force of the driving motor 107 to the shaft assembly 109 is installed.
The clutch assembly 111 is comprised of a lower clutch 115 into which a motor shaft 113 is inserted by force, an upper clutch 117 engaged with, or disengaged from, the lower clutch 115, and a clutch guide device 119 for engaging the upper clutch 117 with, or disengaging the upper clutch 117 from the lower clutch 115, by moving the upper clutch 117 along the motor shaft 113.
The shaft assembly 109 is comprised of a hollow spin basket shaft 139 connected with the spin basket 103, a pulsator shaft 137 disposed in the spin basket shaft 139 coaxially therewith and connected to the pulsator 105, a gear assembly 141 for reducing the rotational velocity of the driving motor 107 and transmitting it to the pulsator 105 during a washing operation or a rinsing operation, an outer casing 142 for encompassing them, and a brake assembly 143 for controlling the rotation of the spin basket shaft 139. The outer casing 142 is comprised of an upper casing 147 and a lower casing 149.
The brake assembly 143 is comprised of a cylindrical brake drum 155 surrounding the outer area of the gear assembly 141, a brake band 165 installed on an outer side of the brake drum 155 so as to control the rotation of the brake drum 155, and a brake lever 133 for operating the brake band 165 so as to be contacted with, or distanced from, the periphery of the brake drum 155.
A brake lever shaft 167 in parallel with the rotational axis of the brake drum 155 is installed on the brake lever 133, and a brake link 169 is installed on the end of the brake lever 133. A brake spring 171 for applying an elastic force to the brake lever 133 is installed on the brake lever shaft 167.
During the washing and rinsing operations, the brake lever 133 pulls the brake band 165 with the elastic force of the brake spring 171, and thereby the brake band 165 is contacted with the brake drum 155. Therefore, the rotation of the brake drum 155 is braked by the brake band 165. In this situation, the upper clutch 117 is disengaged from the lower clutch 115.
As the driving motor 107 operates to rotate the motor shaft 113, the rotational velocity of the motor shaft 113 is reduced by the gear assembly 141 and is then transmitted to the pulsator shaft 137. The pulsator 105 is rotated by the rotation of the pulsator shaft 137, whereby a vortex water-flow is generated in the spin basket 103, and thereby, the washing and rinsing operations are performed.
During a dehydrating operation, the brake lever 133 is pulled out by a drain motor (not shown), and thereby the brake lever 133 pivots about the brake lever shaft 167. Then, the brake band 165 is distanced from the brake drum 155, and the brake drum 155 lies in a rotatable state. In this situation, the upper clutch 117 is moved down by the operation of the clutch guide device 119, so as to be engaged with the lower clutch 115.
As the driving motor 107 operates to rotate the motor shaft 113, the upper clutch 117 engaged with the lower clutch 115 is rotated, and thereby, all of the brake drum 155, the spin basket shaft 139, and the pulsator shaft 137 are rotated. Therefore, the pulsator 105 and the spin basket 103 are rotated at the same speed as the rotational speed of the motor shaft 113, and the laundry accommodated in the spin basket 103 is dehydrated by the centrifugal force generated in such a situation.
When the dehydrating operation ends, the driving motor 107 stops operating, and the brake lever 133 is returned to the original state by the brake spring 171. Thus, the brake drum 155 is braked again by the brake band 165. Furthermore, the upper clutch 117 is moved upward by the operation of the clutch guide device 119 so as to be disengaged from the lower clutch 115.
However, in such a conventional washing machine, due to the assembly tolerance occurring while components of the brake assembly 143 are being assembled, the brake band 165 may not release the brake drum 155 properly when the brake lever 133 is driven by the drain motor. More specifically, due to the assembly tolerance, the brake lever 133 cannot be pulled out sufficiently even when the drain motor normally pulls the brake lever 133, and in such a situation, the brake lever 133 is pivoted insufficiently. Therefore, the brake band 165 may remain contacted with the brake drum 155, or the brake drum 155 may not be released normally.
Furthermore, even when the position of the brake lever 133 is changed by the abrasion of the brake band 165, the brake lever 133 cannot be sufficiently pivoted by the drain motor, for which the brake drum 155 may not be released properly.
Meanwhile, since the brake spring 171 for elastically pushing the brake lever 133 is disposed between the brake lever 133 and the upper casing 147 of the shaft assembly 109, the size of the shaft assembly 109 increases as much as the height of the brake spring 171. Moreover, since one end of the brake spring 171 should be supported by the outer casing 142 of the shaft assembly 109 and the other end thereof should be supported by the brake lever 133, it is not easy to assemble them.